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Abstract:Water is used in dairy farming for producing feed, watering the animals, and cleaning and disinfecting barns and equipment. The objective of this study was to investigate the drinking and cleaning water use in a dairy cow barn. The water use was measured on a well-managed commercial dairy farm in North-East Germany. Thirty-eight water meters were installed in a barn with 176 cows and two milking systems (an automatic milking system and a herringbone parlour). Their counts were logged hourly over 806 days. On average, the cows in the automatic milking system used 91.1 (SD 14.3) L drinking water per cow per day, while those in the herringbone parlour used 54.4 (SD 5.3) L per cow per day. The cows drink most of the water during the hours of (natural and artificial) light in the barn. Previously published regression functions of drinking water intake of the cows were reviewed and a new regression function based on the ambient temperature and the milk yield was developed (drinking water intake (L per cow per day) =´27.937 + 0.49ˆmean temperature + 3.15ˆmilk yield (R 2 = 0.67)). The cleaning water demand had a mean of 28.6 (SD 14.8) L per cow per day in the automatic milking system, and a mean of 33.8 (SD 14.1) L per cow per day in the herringbone parlour. These findings show that the total technical water use in the barn makes only a minor contribution to water use in dairy farming compared with the water use for feed production.

With the expected increase in poultry meat consumption water use will increase as well. The objective of this study is to quantify the effects of fattening systems on the water productivity in broiler chicken production with consideration given to conditions in Germany. Four fattening systems were analyzed in terms of water use for feed production, drinking, cleaning, and the parent stock. The fattening systems differed in intensity, ranging from fast fattening with a fattening period of 30 days and a carcass weight of 1.1 kg to slow fattening with a period up to 46 days and a carcass weight of 2.1 kg. During the fattening period the broiler chicken were fed with performance-linked feed. The water productivity of the feed components varied from 0.4 kg dry mass per m 3 water input for soybean meal to 1.8 kg dry mass per m 3 water input for maize. In all fattening systems the water input for feed production accounted for 90 to 93% of the total water input. The share for the parent stock was 7 to 10%, while drinking and cleaning water accounted for less than 1%. For all fattening systems the water productivity was 0.3 kg carcass weight per m 3 water input, 2.8 MJ food energy per m 3 water input and 57 g food protein per m 3 water input. The shorter fattening period and lower feed demand in the more intensive fattening systems were juxtaposed to the higher carcass weight and higher water productivity of the feed components in the more extensive systems.

Abstract. The decreasing availability of water caused by depletion and climate change combined with a growing world population requires the productive use of water now and in the future. The young researcher group "AgroHyd" at the Leibniz-Institute for Agricultural Engineering Potsdam-Bornim (ATB) is currently modeling the water demand for agricultural processes at the farm scale and developing indicators to link the hydrological and agricultural perspectives. The aim of the group is to increase productivity in agriculture by raising water productivity in plant production and livestock farming. The effects of various agronomic measures, individual and in combination, on water productivity are assessed using several indicators. Scenarios of agricultural measures, climate and diets are used to test to what extent the water demand for food production will increase due to growing global change in different regions of the world.

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